As shown in FIG. 14, a conventional anode structure 100 of a typical magnetron, such as those for microwave ovens, which oscillates to generate 2,450 MHz-band microwaves, includes an anode cylinder 101; and vanes 102, which are radially disposed inside the anode cylinder 101.
The vanes 102 are connected together through a pair of large and small strap rings 103, which each are brazed to both upper and lower ends of every other vane 102 in the circumferential direction.
In an electron interaction space surrounded by free ends of a plurality of vanes 102, a spiral cathode 104 is disposed along an axis of the anode cylinder 101. Both ends of the cathode 104 are fixed to an output side end hat 105 and an input side end hat 106.
To both ends of the anode cylinder 101, pole pieces 107 and 108, which are almost funnel-shaped, are fixed.
The strap rings 103 are designed to alternately keep the vanes 102 at the same potential. As described above, the structure in which a pair of large and small strap rings 103 are provided at both upper and lower ends of the vanes 102 is currently popular. There are other structures, such as a structure in which the upper and lower ends are each provided with one strap ring, or a structure in which one of the upper and lower ends is provided with two or more strap rings, or a structure in which two strap rings are provided in an up-down direction central portion of vanes.